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o Add patch to avoid divide-by-zero trap o Merge patches for gnuplot-3.7.1 PR: 16120 Submitted by: Akio Morita <amorita@meadow.scphys.kyoto-u.ac.jp> Reviewed by: maintainer
81 lines
3.1 KiB
Plaintext
81 lines
3.1 KiB
Plaintext
# contour.c.fix.991130
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--- contour.c.ORIG Thu Dec 3 22:23:46 1998
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+++ contour.c Wed Dec 1 21:07:24 1999
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@@ -536,8 +536,8 @@
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struct edge_struct **p_edges; /* list of edges output */
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{
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int i, j, grid_x_max = iso_lines->p_count;
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- struct edge_struct *p_edge1, *p_edge2, *edge0, *edge1, *edge2, *pe_tail,
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- *pe_tail1, *pe_tail2, *pe_temp;
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+ struct edge_struct *p_edge1, *p_edge2, *edge0, *edge1, *edge2,
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+ *pe_tail, *pe_tail2, *pe_temp;
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struct poly_struct *pp_tail, *lower_tri, *upper_tri;
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struct coordinate GPHUGE *p_vrtx1, GPHUGE * p_vrtx2; /* HBB 980308: need to tag *each* of them as GPHUGE! */
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@@ -545,14 +545,14 @@
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(*p_edges) = pe_tail = NULL;
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p_vrtx1 = iso_lines->points; /* first row of vertices */
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- p_edge1 = pe_tail1 = NULL; /* clear list of edges */
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+ p_edge1 = pe_tail = NULL; /* clear list of edges */
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/* Generate edges of first row */
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+ /* HBB 19991130: removed effectively unused variable 'pe_tail1' */
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for (j = 0; j < grid_x_max - 1; j++)
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- add_edge(p_vrtx1 + j, p_vrtx1 + j + 1, &p_edge1, &pe_tail1);
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+ add_edge(p_vrtx1 + j, p_vrtx1 + j + 1, &p_edge1, &pe_tail);
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(*p_edges) = p_edge1; /* update main list */
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- pe_tail = pe_tail1;
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/*
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@@ -562,10 +562,16 @@
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* (pe_tail points on last edge).
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*
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* Temporary pointers:
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- * 1. p_edge2: Top horizontal edge list: ----------------------- 2
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- * 2. pe_tail: middle edge list: |\ |\ |\ |\ |\ |\ |
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+ * 1. p_edge2: Top horizontal edge list: +-----------------------+ 2
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+ * 2. p_tail : end of middle edge list: |\ |\ |\ |\ |\ |\ |
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* | \| \| \| \| \| \|
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- * 3. p_edge1: Bottom horizontal edge list: ----------------------- 1
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+ * 3. p_edge1: Bottom horizontal edge list: +-----------------------+ 1
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+ *
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+ * pe_tail2 : end of list beginning at p_edge2
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+ * pe_temp : position inside list beginning at p_edge1
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+ * p_edges : head of the master edge list (part of our output)
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+ * p_vrtx1 : start of lower row of input vertices
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+ * p_vrtx2 : start of higher row of input vertices
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*
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* The routine generates two triangle Lower Upper 1
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* upper one and lower one: | \ ----
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@@ -633,14 +639,21 @@
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upper_tri = add_poly(edge0, edge1, edge2, p_polys, &pp_tail);
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}
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- if ((*p_edges)) { /* Chain new edges to main list. */
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- pe_tail->next = p_edge2;
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- pe_tail = pe_tail2;
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- } else {
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- (*p_edges) = p_edge2;
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- pe_tail = pe_tail2;
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+ if (p_edge2) {
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+ /* HBB 19991130 bugfix: if p_edge2 list is empty,
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+ * don't change p_edges list! Crashes by access
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+ * to NULL pointer pe_tail, the second time through,
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+ * otherwise */
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+ if ((*p_edges)) { /* Chain new edges to main list. */
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+ pe_tail->next = p_edge2;
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+ pe_tail = pe_tail2;
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+ } else {
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+ (*p_edges) = p_edge2;
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+ pe_tail = pe_tail2;
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+ }
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}
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+ /* this row finished, move list heads up one row: */
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p_edge1 = p_edge2;
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p_vrtx1 = p_vrtx2;
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}
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